/*
 * Copyright (C) 2008-2017 TrinityCore <http://www.trinitycore.org/>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef _QUERY_CALLBACK_H
#define _QUERY_CALLBACK_H

#include "Define.h"
#include "DatabaseEnvFwd.h"
#include <functional>
#include <future>
#include <list>
#include <queue>
#include <utility>

class TC_DATABASE_API QueryCallback
{
public:
    explicit QueryCallback(QueryResultFuture&& result);
    explicit QueryCallback(PreparedQueryResultFuture&& result);
    explicit QueryCallback(TransactionCompleteFuture&& result);
    QueryCallback(QueryCallback&& right);
    QueryCallback& operator=(QueryCallback&& right);
    virtual ~QueryCallback();

    // Transaction
    QueryCallback&& WithCallback(std::function<void()>&& callback);
    // String query
    QueryCallback&& WithCallback(std::function<void(QueryResult)>&& callback);
    // Prepared query
    QueryCallback&& WithPreparedCallback(std::function<void(PreparedQueryResult)>&& callback);

    // Transaction
    QueryCallback&& WithChainingCallback(std::function<void(QueryCallback&)>&& callback);
    // String query
    QueryCallback&& WithChainingCallback(std::function<void(QueryCallback&, QueryResult)>&& callback);
    // Prepared query
    QueryCallback&& WithChainingPreparedCallback(std::function<void(QueryCallback&, PreparedQueryResult)>&& callback);

    // Moves std::future from next to this object
    void SetNextQuery(QueryCallback&& next);

    enum Status
    {
        NotReady,
        NextStep,
        Completed
    };

    enum QueryType
    {
        STRING_QUERY,
        PREPARED_QUERY,
        TRANSACTION,
    };

    virtual Status InvokeIfReady();

private:
    QueryCallback(QueryCallback const& right) = delete;
    QueryCallback& operator=(QueryCallback const& right) = delete;

    template<typename T> friend void ConstructActiveMember(T* obj);
    template<typename T> friend void DestroyActiveMember(T* obj);
    template<typename T> friend void MoveFrom(T* to, T&& from);

    union
    {
        QueryResultFuture _string;
        PreparedQueryResultFuture _prepared;
        TransactionCompleteFuture _transaction;
    };
    QueryType _type;

    struct QueryCallbackData;
    std::queue<QueryCallbackData, std::list<QueryCallbackData>> _callbacks;
};

#endif // _QUERY_CALLBACK_H
